Film Forming Apparatus

ABSTRACT

A film forming apparatus includes: process container to generate vacuum atmosphere; mounting part to mount substrate; heating part to heat the substrate mounted on the mounting part; gas supply part installed at rear side of the substrate mounted on the mounting part and configured to supply film forming gas toward front side of the substrate along surface of the substrate and flow rate of the film forming gas becomes uniform in width direction of flow of the film forming gas; rotation mechanism to rotate the mounting part about axis orthogonal to the substrate when the film forming gas is supplied to the substrate; film thickness adjustment part to adjust film thickness distribution of film on the substrate in flow direction of the film forming gas when viewed in state where the mounting part is stopped; and exhaust port provided at the front side of the substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No.2015-190007, filed on Sep. 28, 2015, in the Japan Patent Office, thedisclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

The present disclosure relates to a technique of forming a film bysupplying a film forming gas to a surface of a substrate.

BACKGROUND

Along with the demand for pattern miniaturization of a semiconductordevice, there is a variety of stringent requirements with respect to aprocess such as a film forming process, an etching process or the like.A double patterning process known as one of pattern miniaturizationprocesses is taken as an example. In this process, a thin film is firstformed on a pattern of a silicon oxide film. Films called sidewalls areformed by etching on both sidewalls of a concave portion thatconstitutes the pattern of the silicon oxide film. Subsequently, a hardmask is formed by etching a base film using the sidewalls remainingafter removing a resist as a mask pattern.

In order to improve the quality of a pattern generated by sidewalls, itis necessary to match the in-plane uniformity of a thickness of a thinfilm and the etching characteristic of an etching apparatus. Thedistribution of an etching rate, which is the etching characteristic, isformed in a concentric shape so that, for example, the etching rate ishigh in a central portion of a substrate and low in a peripheral edgeportion thereof. Thus, a concentric film thickness distribution isrequired even in a film forming process.

There is well-known a method in which a film forming gas is suppliedfrom above a substrate using a shower head of a film forming apparatus.In this method, there may be a case where a singular point, at whichcoverage or a film quality is different, appears just below the holes ofthe shower head. For example, when a concentric thin film is formed byrotating a semiconductor wafer (hereinafter referred to as a “wafer”)which is a substrate to be processed, there is a problem in that acircular defective portion is formed in the wafer due to the singularpoint.

Furthermore, in the related art, a change in an apparatus configurationsuch as a change in a process container structure of a film formingapparatus or the like has been performed in order to obtain a concentricfilm thickness distribution. However, the proper concentric filmthickness distribution available after a film formation varies dependingon the film quality or process of substrate processing. For that reason,in the case where the concentric film thickness distribution is adjustedby changing the apparatus configuration, it is necessary to optimizehardware for every film quality or process. This leads to an increase inthe time or cost required in optimizing the hardware.

In the related art, there is known a technique in which the thickness ofa film formed on a wafer is made uniform by disposing a plurality of gasinjection parts in a width direction with respect to a film forming gassupply direction, changing a velocity of a gas flow in the widthdirection with respect to the film forming gas supply direction androtating the wafer. However, if a film is formed by supplying a filmforming gas from a lateral side, there is a problem in that a gas flowis not stabilized at a downstream side and a film thickness is notuniform.

Furthermore, in the related art, there is known a technique in which aconcentric film thickness distribution is obtained by adjusting agradient of a film thickness distribution in a radial direction when awafer is not rotated, and rotating the wafer. However, this techniquecannot solve the problems addressed in the present disclosure.

SUMMARY

Some embodiments of the present disclosure provide a technique capableof adjusting a concentric film thickness distribution of a thin filmformed on a substrate.

According to one embodiment of the present disclosure, there is provideda film forming apparatus, including: a process container configured togenerate a vacuum atmosphere; a mounting part provided within theprocess container and configured to mount a substrate thereon; a heatingpart configured to heat an opposite side from a mounting surface of themounting part to heat the substrate mounted on the mounting part; a gassupply part installed at a rear side of the substrate mounted on themounting part and configured to supply a film forming gas so that thefilm forming gas flows toward a front side of the substrate along asurface of the substrate over the entire surface of the substrate and sothat a flow rate of the film forming gas becomes uniform in a widthdirection of a flow of the film forming gas; a rotation mechanismconfigured to rotate the mounting part about an axis orthogonal to thesubstrate when the film forming gas is supplied to the substrate; a filmthickness adjustment part configured to adjust a film thicknessdistribution of a film on the substrate in a flow direction of the filmforming gas when viewed in a state in which the mounting part isstopped; and an exhaust port provided at the front side of thesubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the presentdisclosure, and together with the general description given above andthe detailed description of the embodiments given below, serve toexplain the principles of the present disclosure.

FIG. 1 is a vertical sectional side view of a film forming apparatusaccording to a first embodiment.

FIG. 2 is a plane view of the film forming apparatus according to thefirst embodiment.

FIG. 3 is a perspective view illustrating an upper side configuration ofa dilution gas supply path.

FIG. 4 is a schematic view illustrating an action of the film formingapparatus according to the first embodiment.

FIG. 5 is a schematic view illustrating a concentration distribution ofa film forming gas.

FIG. 6 is a schematic view illustrating the concentration distributionof the film forming gas in a plane.

FIG. 7 is a schematic view illustrating the concentration distributionof the film forming gas.

FIG. 8 is a vertical sectional side view of a film forming apparatusaccording to a second embodiment.

FIG. 9 is a plane view of the film forming apparatus according to thesecond embodiment.

FIG. 10 is a vertical sectional side view of a film forming apparatusaccording to a third embodiment.

FIG. 11 is a vertical sectional side view of a film forming apparatusaccording to a fourth embodiment.

FIG. 12 is a vertical sectional side view illustrating another exampleof an embodiment of the present disclosure.

FIG. 13 is a plane view illustrating a high-frequency antenna accordingto another example of an embodiment of the present disclosure.

FIG. 14 is an explanatory view illustrating a set value of a filmthickness distribution in example 1.

FIG. 15 is a characteristic diagram illustrating a film thicknessdistribution in example 1.

FIG. 16 is an explanatory view illustrating a set value of a filmthickness distribution in example 2.

FIG. 17 is a characteristic diagram illustrating a film thicknessdistribution in example 2.

FIG. 18 is an explanatory view illustrating a set value of a filmthickness distribution in example 3.

FIG. 19 is a characteristic diagram illustrating a film thicknessdistribution in example 3.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments, examples ofwhich are illustrated in the accompanying drawings. In the followingdetailed description, numerous specific details are set forth in orderto provide a thorough understanding of the present disclosure. However,it will be apparent to one of ordinary skill in the art that the presentdisclosure may be practiced without these specific details. In otherinstances, well-known methods, procedures, systems, and components havenot been described in detail so as not to unnecessarily obscure aspectsof the various embodiments.

First Embodiment

As a film forming apparatus according to a first embodiment, there willbe described a film forming apparatus that implements a so-called atomiclayer deposition (ALD) method which performs a film formation byalternately supplying a raw material gas and a reaction gas andlaminating an atomic layer or a molecular layer. As illustrated in FIG.1, the film forming apparatus includes a process container 1 as a vacuumcontainer in which a film forming process is performed with respect to awafer W as a substrate. The process container 1 includes a lowercontainer portion 11 which is a cylindrical portion opened at its upperside and a square-tube-shaped upper container portion 12 which iscontinuously installed on the lower container portion 11 so as tosurround an upper part of the lower container portion 11. The internalspace of the lower container portion 11 and the internal space of theupper container portion 12 communicate with each other. The internalspace of the upper container portion 12 constitutes a processing spacein which a film forming process is performed. A loading/unloading gate13 for loading and unloading the wafer W and a gate valve 14 for openingand closing the loading/unloading gate 13 are provided in a sidewallsurface of the lower container portion 11.

A mounting table 2, which is a substrate mounting part for mounting thewafer W, is disposed within the process container 1. The mounting table2 is formed in a disc shape by a metal such as, e.g., aluminum or thelike. A heater 21 for heating the wafer W to a film forming temperatureof, for example, 100 to 400 degrees C. is embedded within the mountingtable 2. The clearance between the side surface of the mounting table 2and the sidewall of the lower container portion 11 is set at such asmall size as not to obstruct the elevating movement of the mountingtable 2. The processing space and the lower space are partitioned by themounting table 2.

An elevating plate 24 is connected to the central portion of the lowersurface of the mounting table 2 via a shaft portion 23 extending in anup-down direction through an opening portion 15 formed on the bottomsurface of the process container 1. A bearing portion 16 configured toallow the shaft portion 23 to make an elevating and rotating movement isinstalled between the opening portion 15 and the shaft portion 23 inorder to air-tightly isolate the atmosphere of the process container 1from the outside. A motor 25 is installed on the upper surface of theelevating plate 24. The motor 25 is connected to the shaft portion 23via a belt 27. The shaft portion 23 and the mounting table 2 are rotatedabout a vertical axis by rotating the belt 27 with the motor 25. Themotor 25 and the belt 27 constitute a rotation mechanism 20.

An elevator mechanism 26 is installed at the lower surface side of theelevating plate 24. The shaft portion 23 and the mounting table 2 areone-piece formed with the elevating plate 24 and are moved up and downby the elevator mechanism 26. When a film forming process is performedby supplying a film forming gas to the wafer W, the mounting table 2 ismoved to a processing position indicated by a solid line in FIG. 1, inwhich, for example, the front surface of the wafer W is substantiallyflush with the upper surface of the inner bottom wall of the uppercontainer portion 12. When the wafer W is delivered between the mountingtable 2 and an external transfer mechanism, the mounting table 2 ismoved down from the processing position to a lower position which is aloading/unloading position indicated by a chain line in FIG. 1.

Subsequently, the upper container portion 12 will be described withreference to FIG. 2. For example, if it is assumed that the left sideand the right side viewed from the wafer W are a front side and a rearside, respectively, an exhaust groove 31 as an exhaust port having arectangular cross section, which extends in the width direction, namelyin the left-right direction at the front side of the wafer W, is formedat one longitudinal end within the upper container portion 12. The uppersurface side of the exhaust groove 31 is opened on the bottom surface ofthe upper container portion 12. A lid portion 32 having a plurality ofslits 33 respectively extending in the width direction of the uppercontainer portion 12 and arranged side by side in the longitudinaldirection of the upper container portion 12 is installed in the openingportion of the exhaust groove 31. An exhaust pipe 34 is connected to thecenter of the bottom portion of the exhaust groove 31. A pressureregulation part 35 and an exhaust valve 36 are installed in the exhaustpipe 34 sequentially from the side of the exhaust groove 31. The exhaustpipe 34 is connected to a vacuum exhaust pump not shown.

At the rear side of the interior of the upper container portion 12, afilm forming gas injection part 4 formed of a tubular member andconfigured to constitute a gas supply part is installed so as to extendin the left-right direction. A slit 41 as a film forming gas injectionhole extending in the longitudinal direction of the film forming gasinjection part 4 is formed in the film forming gas injection part 4 sothat the slit 41 is opened toward the front side. The slit 41 is formedat a length larger than the width of the wafer W so as to cover theentire surface of the wafer W in a plane view. The slit 41 is formed sothat a film forming gas can pass through the entire surface of the waferW.

A gas supply pipe 40 is connected to the longitudinal center of the filmforming gas injection part 4 at the rear side thereof. A raw materialgas supply pipe 42 for supplying a raw material gas, a reaction gassupply pipe 46 for supplying a reaction gas reacting with the rawmaterial gas and a replacement gas supply pipe 60 for supplying areplacement gas are merged with the gas supply pipe 40. The other end ofthe raw material gas supply pipe 42 is connected to a supply source 43of TiCl₄ which is a raw material gas. A flow rate adjustment part 45 anda valve 44 are installed in the raw material gas supply pipe 42sequentially from the side of the TiCl₄ supply source 43. The other endof the reaction gas supply pipe 46 is connected to a supply source 47 ofH₂O which is a reaction gas. A flow rate adjustment part 49 and a valve48 are installed in the reaction gas supply pipe 46 sequentially fromthe side of the H₂O supply source 47. In this example, the term “filmforming gas” is used to indicate the raw material gas and the reactiongas. A nitrogen (N₂) gas supply source 61 is connected to the other endof the replacement gas supply pipe 60. A flow rate adjustment part 62and a valve 63 are installed in the replacement gas supply pipe 60sequentially from the side of the N₂ supply source 61.

As illustrated in FIG. 1, in the ceiling portion of the processcontainer 1 facing the mounting table 2, dilution gas supply ports 5(each of which includes an opening portion and a portion of a supplypath continuous with the opening portion) for supplying a concentrationadjustment gas which adjusts the concentration of the film forming gas,for example a nitrogen gas as a dilution gas, are formed at a pluralityof points, for example, at five points at regular intervals, along theflow direction of the film forming gas. As illustrated in FIG. 2, eachof the dilution gas supply ports 5 is formed in the shape of a slitextending in the left-right direction (in the width direction of theflow of the film forming gas) and extending in the width direction so asto cover the entire surface of the wafer W in a plane view. In thisexample, the length dimension of the dilution gas supply ports 5 in theleft-right direction (in the width direction of the flow of the filmforming gas) is set at the same length dimension as the length dimensionof the slit 41 of the film forming gas injection part 4 in theleft-right direction (in the width direction of the flow of the filmforming gas).

As illustrated in FIG. 1, each of the dilution gas supply ports 5includes a dilution gas supply path 50 obliquely formed in the ceilingof the upper container portion 12 so that the dilution gas is obliquelyinjected toward the front side (toward the exhaust groove 31). Thedilution gas supply path 50 is formed so as to extend in the left-rightdirection (in the width direction of the flow of the film forming gas)and is configured so that the dilution gas is supplied from each of thedilution gas supply ports 5 toward the upper surface of the wafer Wmounted on the mounting table 2 at a uniform flow rate in the widthdirection (the left-right direction). As illustrated in FIGS. 1 and 3, asquare-tube-shaped buffer chamber 5 a extending in the width directionof the flow of the dilution gas (in the left-right direction) is formedat the upper side (upstream side) of the dilution gas supply path 50. Acommunication path 5 b extending through the central portion of theceiling surface of the buffer chamber 5 a is formed at the upper side ofthe buffer chamber 5 a. The upper end of the communication path 5 b isopened toward the upper side of the process container 1. A dilution gassupply pipe 51 is connected to the upper end of the communication path 5b. A dilution gas supply source 52 is installed at the upstream end ofthe dilution gas supply pipe 51. A flow rate adjustment part 53 and avalve 54 are installed in the dilution gas supply pipe 51 sequentiallyfrom the upstream side. The low rate adjustment part 53 and the valve 54correspond to a dilution gas adjustment part 55.

Subsequently, descriptions will be made on the action of the embodimentof the present disclosure. First, the wafer W as a substrate to beprocessed is mounted on the mounting table 2 by, for example, anexternal transfer arm not shown and is heated by the heater 21. Then,the gate valve 14 is closed and the process container 1 is sealed.Thereafter, for example, the supply of an N₂ gas from the film forminggas injection part 4 is started and the exhaust from the exhaust groove31 is performed to regulate the internal pressure of the processcontainer 1. Then, the mounting table 2 is moved up to the processingposition.

Thereafter, a film forming process is performed by an ALD method usingTiCl₄, which is a raw material gas, and H₂O, which is a reaction gas, asfilm forming gases. Descriptions will be made on a method of supplyingthese film forming gases to the wafer W. As illustrated in FIG. 4, whileperforming the exhaust from the exhaust groove 31, the supply of thefilm forming gases toward the wafer W mounted on the mounting table 2 isstarted and the dilution gas is supplied from the respective dilutiongas supply ports 5 toward the wafer W. When introduced from the gassupply pipe 40 into the film forming gas injection part 4, the filmforming gases are uniformly diffused within the film forming gasinjection part 4. Thereafter, the film forming gases are supplied fromthe slit 41 of the film forming gas injection part 4 at a uniform flowrate in the width direction of the wafer W (in the left-rightdirection). The film forming gases flow along the surface of the wafer Wover the entire surface. Thereafter, the film forming gases areintroduced into the exhaust groove 31 while maintaining a parallel flowand are exhausted from the exhaust pipe 34.

FIG. 5 is a schematic view illustrating a film forming gasconcentration. A to G in FIG. 5 correspond to points (positions) A to Gin FIG. 4. At point A existing at the upstream side of a film forminggas flow in FIG. 5, which is a peripheral edge portion (rear endportion) of the wafer W, the film forming gas has substantially the sameconcentration as the concentration of the raw material gas and thereaction gas in the gas supplied from the film forming gas injectionpart 4. Since the film forming gas is consumed by performing a filmforming process with respect to the wafer W, the concentration of thefilm forming gas in the vicinity of the surface of the wafer W isgradually reduced toward the front surface (toward the exhaust groove31), namely toward the downstream side. Schematically saying, theconcentration of the film forming gas is diluted at point B of the mostupstream side where the film forming gas and the dilution gas flowingalong the surface of the wafer W are merged with each other. The dilutedfilm forming gas further flows toward the front side. The diluted filmforming gas is further diluted at point C where the film forming gas issubsequently merged with the dilution gas. Then, the film forming gasflows toward the front side while being diluted in the order of pointsD, E and F.

Thus, for example, as indicated by a graph in FIG. 5, the concentrationof the film forming gas (the concentration of the raw material gas orthe reaction gas) grows thinner toward the downstream side. At thistime, the film forming gas is supplied at a uniform flow rate in thewidth direction of the flow of the film forming gas and the dilution gasis supplied from the slit-shaped dilution gas supply ports 5 extendingin the width direction of the flow of the film forming gas at a uniformflow rate in the width direction of the flow of the film forming gas.Since the concentration of the film forming gas is changed in the flowdirection of the film forming gas, as illustrated by a schematic view inFIG. 6, the concentration of the film forming gas becomes uniform in thewidth direction of the flow of the film forming gas. FIG. 6 is a viewschematically illustrating the concentration distribution in the flowdirection of the film forming gas. In FIG. 6, the film forming gashaving a higher concentration is distributed in a region in which thehatching density is higher.

Then, the wafer W is rotated about a vertical axis by driving therotation mechanism 20. If the wafer W is rotated in the atmosphere inwhich the concentration of the film forming gas is uniform in the widthdirection and is continuously changed in one direction as illustrated inFIG. 6, the portion of the wafer W other than the center (rotationcenter) thereof is repeatedly moved between a region in which theconcentration of the film forming gas is high and a region in which theconcentration of the film forming gas is low. That is to say, whenviewed from the respective portions of the wafer W, a state in which theconcentration of the film forming gas in the atmosphere is graduallydecreased and then gradually increased is repeated. When the wafer W isrotated once, the portion having the same distance from the centerpasses through the same region. Thus, the film thickness in thecircumferential direction is uniform. The film thickness is determineddepending on the concentration change pattern with respect to the timechange when the portion of the wafer W is rotated once. Accordingly, thethin film formed on the surface of the wafer W has a concentric filmthickness distribution which is determined depending on theconcentration distribution in the flow direction of the film forming gasin the vicinity of the surface of the wafer W. As described above, theconcentration distribution of the film forming gas is determineddepending on the degree of dilution by the dilution gas supplied fromthe respective dilution gas supply ports 5. Thus, the concentrationdistribution of the film forming gas can be adjusted by changing theflow rate of the dilution gas supplied from the respective dilution gassupply ports 5 with the dilution gas adjustment part 55.

Descriptions will be made on a case where a concentration distribution,in which the concentration of the film forming gas is linearly reducedwith respect to the distance from the slit 41, for example, as indicatedby a dotted line in the graph of FIG. 5, is formed by adjusting thedilution gas supplied from the respective dilution gas supply ports 5.In the case of such a concentration distribution, the deposition ratewhen the wafer W passes through the more upstream side of the flow ofthe film forming gas than the center of the wafer W is higher than thedeposition rate in the central portion of the wafer W. The depositionrate when the wafer W passes through the more downstream side of theflow of the film forming gas than the center of the wafer W is lowerthan the deposition rate in the central portion of the wafer W. Sincethe slope of the graph is a straight line, the rising amount of thedeposition rate at the upstream side is equal to the falling amount ofthe deposition rate at the downstream side. Accordingly, as can berioted from the examples which will be described later, the filmthickness obtained when the central region of the wafer W is rotatedonce becomes substantially equal to the film thickness obtained when theperipheral region of the wafer W is rotated once. Thus, the film isformed so that the film thickness on the surface of the wafer W becomesuniform.

If the supply amount of the dilution gas supplied from the dilution gassupply ports 5 is gradually increased from the upstream side toward thedownstream s indicated by a solid line in the graph of FIG. 5, thereduction in the concentration of the film forming gas becomes smallerat the upstream side and becomes larger at the downstream side. In thisconcentration distribution of the film forming gas, for example, theincrease in the concentration in the central region of the wafer Wbetween points C and E in FIG. 5 is larger than the increase in theconcentration indicated by a dotted line in FIG. 5. Thus, a film havinga thickness increased in proportion to the rising amount of theconcentration is formed. In contrast, the rising amount of theconcentration with respect to the concentrations between points A and Cand between points E and F indicated by a dotted line in FIG. 5 issmaller than the rising amount of the concentration with respect to theconcentration between points C and E indicated by a dotted line in FIG.5. A film is formed on the peripheral portion the wafer W while theperipheral portion of the wafer W is moved over the range between pointsA and G. The deposition rate when the peripheral portion of the wafer Wpasses through the ranges between points A and C and points E and F islower than the deposition rate in the range between points C and E inFIG. 5. Thus, a film is more difficult to be formed in the peripheralposition of the wafer W than in the central position thereof.Consequently, a concentric film thickness distribution having a largefilm thickness in the central portion and a small film thickness in theperipheral portion is formed on the wafer W.

Furthermore, by increasing the gas injection amount of the upstream-sidedilution gas supply ports 5, for example, the dilution gas supply ports5 which supply the dilution gas toward points B and C in FIG. 4, and byreducing the gas injection amount of the downstream-side dilution gassupply ports 5, for example, the dilution gas supply ports 5 whichsupply the dilution gas toward points E and F in FIG. 4, it is possibleto form a concentration distribution in which, as indicated in the graphof FIG. 7, the reduction in the concentration of the film forming gas islarge at the upstream side and the reduction in the concentration of thefilm forming gas is small at the downstream side. According to thisconcentration distribution of the film forming gas, for example, in thecentral region of the wafer W between points C and E in FIG. 7, theconcentration is lower than the concentration indicated by a dotted linein FIG. 7 and the film is made thin just as much as the falling amountof the concentration. In contrast, in the peripheral region, the fallingamount of the concentration with respect to the concentrations betweenpoints A and C and between points E and F indicated by a dotted line inFIG. 7 is smaller than the falling amount of the concentration withrespect to the concentration between points C and E indicated by adotted line in FIG. 7. Accordingly, the deposition rate when theperipheral portion of the wafer W passes through the ranges betweenpoints A and C and points E and F is higher than the deposition rate inthe range between points C and E in FIG. 7. Thus, a film is more easilyformed in the peripheral position of the wafer W than in the centralposition thereof. Consequently, a concentric film thickness distributionhaving a small film thickness in the central portion and a large filmthickness in the peripheral portion is formed on the wafer W.Accordingly, by adjusting the flow rate of the dilution gas with thedilution gas adjustment part 55, it is possible to adjust theconcentration distribution of the film forming gas and to adjust thethickness of the film formed on the wafer W. Thus, the dilution gasadjustment part 55 corresponds to a film thickness adjustment portion.

In this way, the film forming gas is supplied to the surface of wafer Wat a uniform flow rate in the width direction and the concentration ofthe film forming gas is continuously changed in the flow direction ofthe film forming gas. On the surface of the wafer W, the flow of thefilm forming gas is easily disturbed particularly at the downstreamside. For that reason, the film forming gas is more easily mixed in thewidth direction than in the flow direction of the film forming gas.Thus, even if one tries to generate a difference in the concentration ofthe film forming gas in the width direction of the flow of the filmforming gas, it is difficult to maintain the concentration difference.In contrast, a flow moving toward one side is formed in the flowdirection of the film forming gas. Thus, the film forming gas isdifficult to be mixed in the flow direction of the film forming gas.Accordingly, by continuously changing the concentration of the filmforming gas in the flow direction of the film forming gas, it ispossible to stably form an atmosphere in which the difference in theconcentration of the film forming gas is maintained in one direction.

The film forming process will be described again. In the film formingprocess using the ALD method, a TiCl₄ gas as a raw material gas is firstsupplied for, e.g., 1 second. The valve 44 is closed. TiCl₄ is allowedto be adsorbed onto the surface of the wafer W. Subsequently, areplacement gas (N₂ gas) is supplied into the process container 1 toreplace the internal atmosphere of the process container 1. Then, if areaction gas (H₂O) gas is supplied into the process container 1, amolecular film of TiO₂ is formed on the surface of the wafer W by thehydrolysis and dechlorination reaction. Thereafter, the replacement gasis supplied into the process container 1 to replace the internalatmosphere of the process container 1. By repeating, multiple times, acycle of supplying the raw material gas containing TiCl₄, thereplacement gas, the reaction gas and the replacement gas into theprocess container 1 in this way, molecular layers of TiCl₄ are laminatedto form a TiO₂ film having a predetermined thickness.

According to the embodiment described above, in the film formingapparatus which forms a film by supplying the film forming gas to thesurface of the wafer W, the film forming gas is supplied as aunidirectional flow to the surface of the wafer W at a uniform flow ratein the width direction. The dilution gas is supplied from the dilutiongas supply ports 5 arranged side by side in the flow direction of thefilm forming gas, thereby continuously changing the concentration of thefilm forming gas in the flow direction of the film forming gas. Underthis atmosphere, a film is formed on the surface of the wafer W whilerotating the wafer W. Accordingly, the thickness distribution of thethin film formed on the wafer W is formed in a concentric shape. Byadjusting the amount of the dilution gas supplied from the dilution gassupply ports 5 and adjusting the concentration distribution in the flowdirection of the film forming gas, it is possible to adjust theconcentric film thickness distribution. Furthermore, the concentrationof the film forming gas in the flow direction of the film forming gas iscontinuously changed. Therefore, the concentration distribution of thefilm forming gas is less susceptible to the influence of flow turbulenceand is stabilized. It is therefore possible to stably obtain an expectedfilm thickness distribution in the thin film thus formed. By obtaining afilm thickness distribution corresponding to the in-plane tendency of anetching apparatus, it is possible to improve the in-plane uniformityafter an etching process.

Furthermore, the concentration-distribution-adjusting gas supplied tothe flow of the film forming gas on the surface of the wafer W is notlimited to the dilution gas such as an inert gas or he like. As analternative example, a gas obtained by diluting a precursor-containingraw material gas with an inert gas may be supplied so as to adjust theconcentration of the film forming gas. Moreover, the concentration ofthe film forming gas may be adjusted by supplying the film forming gasrather than the dilution gas from the dilution gas supply ports 5illustrated in FIG. 1. In the case where the difference between themaximum flow rate and the minimum flow rate of the film forming gasinjected from the film forming gas injection part 4 in the widthdirection of the flow of the film forming gas falls within a range of±10%, for example, ±100 ml/min when the average flow rate of the filmforming gas is assumed to be 1,000 ml/min, it is possible tosufficiently achieve the above effects. Thus, it can be considered thatthe flow rate of the film forming gas is made uniform in the widthdirection of the flow of the film forming gas.

Second Embodiment

The method of adjusting the film thickness distribution in the flowdirection of the film forming gas with the wafer W kept stationary isnot limited to the method of adjusting the concentration distribution ofthe film forming gas in the flow direction. For example, it may bepossible to use a film forming method in which the deposition rate inthe flow direction of the film forming gas is changed by changing thedistribution of the heating temperature of the wafer W. The secondembodiment is directed to this method. For example, a film formingapparatus illustrated in FIG. 8 is used in this method. Theconfiguration of this film forming apparatus will now be described. Adisc-shaped heating plate 200 is installed within the internal space ofthe mounting table 2 in a spaced-apart relationship with the innersurface of the mounting table 2. Furthermore, a central shaft 201 isinstalled within the shaft portion 23 in a spaced-apart relationshipwith the inner surface of the shaft portion 23. The heating plate 200 isfixed the elevating plate 24 through the central shaft 201. Asillustrated in FIG. 9, rod-shaped heaters 202 constituting a temperatureadjustment part and extending in the direction orthogonal to the flowdirection of the film forming gas, namely in the width direction, areembedded within the heating plate 200 and are arranged side by side inthe flow direction of the film forming gas. The respective heaters 202are configured so that the temperatures thereof can be independentlyadjusted by power supply parts 205. In FIG. 8, some of the power supplyparts 205 are omitted.

Descriptions will be made on the action of the film forming apparatusaccording to the second embodiment. The wafer W is mounted on themounting table 2. Thereafter, heating is started in a state in which,for example, the temperature of the heater 202 disposed at the mostupstream side with respect to the flow of the film forming gas is set ata highest temperature and the temperatures of the heaters 202 disposedat the downstream side are set at gradually decreasing temperatures bythe power supply parts 205 connected to the respective heaters 202. Ifthe film forming gas is supplied to the surface of the wafer W in thisstate, a film is formed such that the film thickness is large at theupstream side with respect to the flow of the film forming gas and isgradually reduced toward the downstream side. This is because thetemperature available at the upstream side is a temperature suitable forthe film formation. Even when the wafer W is rotated, the heating plate200 provided with the heaters 202 is not rotated because the heatingplate 200 is installed in a spaced-apart relationship with the mountingtable 2 and is fixed to the central shaft 201. At this time, the wafer Wis rotated while being heated by the heaters 202. The rotational speedof the wafer W is lowered so that a temperature gradient in which thetemperature decreases from the upstream side of the flow of the filmforming gas toward the downstream side is maintained on the surface ofthe wafer W. Briefly speaking, the wafer W is rotated while maintaininga state in which the deposition rate is high at the upstream side of theflow of the film forming gas and is gradually reduced toward thedownstream side. Thus, a film having a concentric film thicknessdistribution is formed on the wafer W. Accordingly, the thickness of thefilm as formed can be adjusted depending on the temperatures of therespective heaters 202 set by the respective power supply parts 205.

Furthermore, the wafer W may be intermittently rotated when a film isformed by rotating the wafer W in a state in which the temperature ofthe heater 202 disposed at the most upstream side with respect to theflow of the film forming gas is set at a highest temperature and thetemperatures of the heaters 202 disposed at the downstream side are setat gradually decreasing temperatures. For example, a film formingprocess may be performed by alternately repeating a step of stopping thewafer W for 0.5 second and a step of rotating the wafer W by 50 degreesabout a vertical axis. With this configuration, it is possible to form afilm by rotating the wafer W in a state in which a temperature gradientwhere the temperature becomes lower from the upstream side of the flowof the film forming gas toward the downstream side is formed on thesurface of the wafer W. It is therefore possible to achieve the sameeffects as described above.

Since the film forming gas is consumed as it flows along the surface ofthe wafer W, the concentration of the film forming gas becomes lowertoward the downstream side. For that reason, if the temperaturedistribution is formed in the direction differing from the flowdirection of the film forming gas, for example, in the directionorthogonal to the flow direction of the film forming gas, a differencein the thickness of the film as formed is generated even in the regionwhere the temperature remains the same. Thus, the method of forming thetemperature distribution of the wafer W in the flow direction of thefilm forming gas as in the second embodiment is effective.

Third Embodiment

Next, descriptions will be made on a film forming apparatus according toa third embodiment. As illustrated in FIG. 10, in this film formingapparatus, a top plate part 8 which constitutes a facing surface part isinstalled above the mounting table 2. The top plate part 8 is configuredso that the inclination of the top plate part 8 can be changed byrotating the top plate part 8 about a central shaft 80 extending in theleft-right direction (the width direction of the flow of the filmforming gas) at the upper side of the central portion of the wafer W.The flow velocity of the film forming gas flowing along the surface ofthe wafer W becomes lower if the height dimension between the surface ofthe wafer W and the top plate part 8 grows larger. The flow velocitybecomes higher if the height dimension grows smaller. The depositionrate becomes low in the region where the flow velocity of the filmforming gas is high. The deposition rate becomes high in the regionwhere the flow velocity of the film forming gas is low. In the casewhere the turbulence of a gas flow is concerned, the top plate part 8may be installed so as to extend to above the film forming gas injectionpart 4. By rotating the wafer W in this state, it is possible to adjustthe concentric film thickness distribution formed on the wafer W.

Fourth Embodiment

Descriptions will be made on a film forming apparatus according to afourth embodiment. As illustrated in FIG. 11, rod-shaped heaters 9extending over the wafer W in the width direction with respect to theflow direction of the film forming gas are embedded in a top plate part90 as a facing surface part facing the mounting table 2 so that therod-shaped heaters 9 are arranged side by side in the flow direction ofthe film forming gas. For example, the temperatures of the heaters 9disposed at the downstream side are set at higher temperatures and thetemperatures of the heaters 9 disposed at the upstream side are set atlower temperatures.

Thus, if the raw material gas is supplied while heating the raw materialgas with the respective heaters 9, the raw material gas is adsorbed ontothe top plate part 90 by the heat of the heaters 9. Since thetemperatures of the heaters 9 disposed at the downstream side are set athigher temperatures, the adsorption amount of the raw material gasadsorbed onto the top plate part 90 becomes larger at the downstreamside. As a result, the deposition rate on the top plate part 90 growshigher. For that reason, according to the distribution of the adsorptionamount of the raw material gas adsorbed onto the top plate part 90 inthe flow direction of the raw material gas, the adsorption amount of theraw material gas adsorbed onto the surface of the wafer W becomessmaller and the deposition rate becomes lower. Accordingly, by rotatingthe wafer W, it is possible to form a film having a concentric filmthickness distribution on the wafer W. It is possible to adjust theconcentration gradient of the film forming gas from the upstream sidetoward the downstream side on the surface of the wafer W. This makes itpossible to adjust the concentric film thickness distribution formed onthe wafer W.

The present disclosure may be applied to a chemical vapor deposition(CVD) apparatus in which a raw material gas is decomposed or allowed toreact with a reaction gas in a gas phase. Furthermore, the presentdisclosure may be applied to a film forming apparatus in which a filmforming process is performed through the use of plasma. For example, asillustrated in FIG. 12, in the film forming apparatus illustrated inFIG. 8, a dielectric window 91 formed of, for example, a quartz plate,may be installed above the wafer W in a facing relationship with themounting table 2 so as to air-tightly divide the air atmosphere existingabove the dielectric window 91 and the internal vacuum atmosphere of theprocess container 1. For example, four linear high-frequency antennas 92are placed on the dielectric window 91 so as to extend in the directionorthogonal to the flow direction of the film forming gas (in the widthdirection). As illustrated in FIG. 13, for example, two ends of thehigh-frequency antennas 92 disposed at the upstream side in the flowdirection of the film forming gas are connected to each other.Similarly, two ends of the high-frequency antennas 92 disposed at thedownstream side in the flow direction of the film forming gas areconnected to each other. The bunch of the two high-frequency antennas 92disposed at the upstream side and the bunch of the two high-frequencyantennas 92 disposed at the downstream side are connected to each otherat the longitudinal opposite ends thereof. A terminal 93 is installed atone longitudinal end side of the bunch of four high-frequency antennas92 and is connected to a high-frequency power source. The otherlongitudinal end of the bunch of four high-frequency antennas 92 isgrounded. In this film forming apparatus which makes use of plasma, forexample, a raw material gas (TiCl₄ gas) is intermittently supplied whilecontinuously supplying oxygen to the process container 1. When thesupply of the raw material gas is stopped, a high-frequency current issupplied to the high-frequency antennas 92, thereby forming an inductionelectromagnetic field at the upper side of the wafer W and convertingoxygen to plasma. In this way, a film forming process is performed.

EXAMPLES

The following tests were conducted in order to verify the effectsachieved in the embodiment of the present disclosure.

Example 1

In the case where a film forming gas is horizontally supplied toward a300 mm wafer W and where a film thickness distribution of a film formedwhen a film forming process is performed with the wafer W kept stoppedis set so that a film thickness is linearly reduced from the upstreamside of the flow of the film forming gas toward the downstream side, afilm thickness distribution on the surface of the wafer W when a film isformed by rotating the wafer W was found by simulation.

Example 2

The same processing as that of example 1 was performed except that thethickness distribution of a film formed when a film forming process isperformed with the wafer W kept stopped is set so that the filmthickness is gently reduced at the upstream side of the flow of the filmforming gas and is sharply reduced at the downstream side.

Example 3

The same processing as that of example 1 was performed except that thethickness distribution of a film formed when a film forming process isperformed with the wafer W kept stopped is set so that the filmthickness is sharply reduced at the upstream side of the flow of thefilm forming gas and is gently reduced at the downstream side.

FIG. 14 illustrates a film thickness distribution in example 1 when afilm forming process is performed with the wafer W kept stopped. FIG. 15is a characteristic diagram of a film formed in example 1, in which thehorizontal axis indicates the radial distance from the center of thewafer W and the vertical axis indicates the film thickness. FIG. 16illustrates a film thickness distribution in example 2 when a filmforming process is performed without rotating the wafer W. FIG. 17 is acharacteristic diagram of a film formed in example 2, in which thehorizontal axis indicates the radial distance from the center of thewafer W and the vertical axis indicates the film thickness. FIG. 18illustrates a film thickness distribution in example 3 when a filmforming process is performed without rotating the wafer W. FIG. 19 is acharacteristic diagram of a film formed in example 3, in which thehorizontal axis indicates the radial distance from the center of thewafer W and the vertical axis indicates the film thickness.

According to these results, as illustrated in FIGS. 14 and 15, in thecase where the film thickness of the film formed by performing the filmforming process with the wafer W kept stopped is linearly reduced fromthe upstream side of the flow of the film forming gas toward thedownstream side, the film is formed by rotating the wafer W. By doingso, it is possible to obtain a film having high in-plane film thicknessuniformity. In example 1, the value of 61 was 0.1%.

As illustrated in FIGS. 16 and 17, it can be noted that a convex filmhaving a large thickness in the central portion of the wafer W and asmall thickness in the peripheral portion of the wafer W is formed inexample 2. As illustrated in FIGS. 18 and 19, it can be noted that aconcave film having a small thickness in the central portion of thewafer W and a large thickness in the peripheral portion of the wafer Wis formed in example 3.

According to these results, in the present disclosure, it can be saidthat the concentric film thickness distribution formed when the film isformed by rotating the wafer W can be adjusted by adjusting the filmthickness distribution of the film, which is formed when the filmforming process is performed without rotating the wafer W, so as to bechanged in the flow direction of the film forming gas.

According to the present disclosure, when a film is formed by supplyinga film forming gas to a substrate, the film forming gas is supplied as aunidirectional flow moving in a transverse direction along thesubstrate, while rotating the substrate. A film thickness distributionof a thin film formed on the substrate is adjusted in a flow directionof the film forming gas. Accordingly, it is possible to adjust aconcentric film thickness distribution.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosures. Indeed, the embodiments described herein maybe embodied in a variety of other forms. Furthermore, various omissions,substitutions and changes in the form of the embodiments describedherein may be made without departing from the spirit of the disclosures.The accompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of thedisclosures.

What is claimed is:
 1. A film forming apparatus, comprising: a processcontainer configured to generate a vacuum atmosphere; a mounting partprovided within the process container, and configured to mount asubstrate; a heating part configured to heat an opposite side from amounting surface of the mounting part to heat the substrate mounted onthe mounting part; a gas supply part installed at a rear side of thesubstrate mounted on the mounting part, and configured to supply a filmforming gas so that the film forming gas flows toward a front side ofthe substrate along a surface of the substrate over the entire surfaceof the substrate and so that a flow rate of the film forming gas becomesuniform in a width direction of a flow of the film forming gas; arotation mechanism configured to rotate the mounting part about an axisorthogonal to the substrate when the film forming gas is supplied to thesubstrate; a film thickness adjustment part configured to adjust a filmthickness distribution of a film on the substrate in a flow direction ofthe film forming gas when viewed in a state in which the mounting partis stopped; and an exhaust port provided at the front side of thesubstrate.
 2. The apparatus of claim 1, wherein the film thicknessadjustment part is a concentration adjustment gas supply part providedto face the substrate and configured to supply a concentrationadjustment gas to the flow of the film forming gas in order to adjust aconcentration distribution of the film forming gas in the flow directionof the film forming gas.
 3. The apparatus of claim 2, wherein theconcentration adjustment gas supply part is configured to extend in awidth direction of the flow of the film forming gas, the concentrationadjustment gas supply part including a plurality of gas injection portsarranged in the flow direction of the film forming gas to inject adilution gas as the concentration adjustment gas.
 4. The apparatus ofclaim 1, wherein the film thickness adjustment part is a temperatureadjustment part provided independently of the mounting part at theopposite side of the mounting surface of the mounting part from thesubstrate so as to be kept stopped while the mounting part is rotatedand configured to adjust a temperature distribution of the substrate inthe flow direction of the film forming gas.
 5. The apparatus of claim 1,wherein the film thickness adjustment part includes a facing surfacepart configured to face the mounting part through a space for aformation of the flow of the film forming gas, and an adjustmentmechanism configured to adjust a change pattern of a spaced-apartdistance between the substrate and the facing surface part in afront-rear direction of the substrate in order to change a concentrationof the film forming gas in the flow direction of the film forming gas.6. The apparatus of claim 1, wherein the film thickness adjustment partincludes a facing surface part configured to face the mounting partthrough a space for a formation of the flow of the film forming gas, andan adjustment mechanism configured to adjust a temperature distributionof the facing surface part in the flow direction of the film forming gasin order to allow the film forming gas to adhere to the facing surfacepart and in order to change a concentration of the film forming gas inthe flow direction of the film forming gas.